Quick question about Skill Groups.

Hi there, I'm trying to get into modding Torchlight 2. I'm making a new class mod, which I want to balance as well as possible. However, there's a wall I'm walking into right now. The situation is that I want to make three buff skills for my new class that I'm working on. I want the skills to be mutually exclusive with each other. If one buff is active, you can't have the other two active.

I had the feeling Group Name would help with this, as this is the description: "Skills with matching group names are not allowed to cast while another skill matching the group name is active. Case sensitive.". I tried using this with "buff skill 1", but what happens that not only can I not use "buff skill 2" and "buff skill 3", I can't use "buff skill 1" either after using it once, even after the buff wears off. The only way to reset it so I can use "buff skill 1" again is by using the console and resetting my skilltree completely with the command "reset skills", so I can respec into it again.

Is there a better way of doing this, some kind of "if" function that would act as follows:

However, I would also be happy with this:
-Use "buff skill 1"
-"buff skill 1" activates and applies buff
-"buff skill 2" and "buff skill 3" both get grayed out until the buff wears off, making them periodically unusable

Thanks in advance for helping, you'll get back a cool class once it's done!

P.S.
If there's a better place to post this question, do tell, I'm new to these forums as well. Thanks!